The symptoms of lactose intolerance appear after you have eaten or drunk something that contains lactose. They are usually mild. Symptoms include nausea, feeling bloated, stomach pains or cramps, diarrhoea, flatulence, loud bowel sounds or sometimes having an urgent need to have a bowel movement between 30min-2hrs after eating or drinking something that contains lactose. These symptoms may be caused by problems other than lactose intolerance. If you have any of these symptoms, see your doctor for advice.
Attribution: BUPA